Technical innovation of Leader Dredger
Dredging has always played a very important role in such projects as channel dredging, land reclamation, wharf construction, flood control, and pond dredging.
Large modern dredgers are special engineering vessels with complex structures and high technical content. The international dredger market was monopolized by a few European countries. However, with the rapid growth of Chinese technology, Chinese dredgers have gradually gained high ratings for high quality, low price, convenient transportation, fast delivery, customizable, etc.
“Leader Dredger and the design team of Shanghai Jiaotong University who designed the “Tiankun” have a close dredger innovation cooperation, focusing on the hull size of the dredger, cutter bridge, winch system, hydraulic system, positioning pile, mud pump system and its Professional analysis and design of power system, environmental aspects, vibration and noise issues”
Calculation And Simulation
In order to verify and improve the design of almost all systems and structures installed on ships, computer-aided calculations and simulations are widely used.
All important and heavy load areas are calculated using FEM. Both static and dynamic loads are simulated. Large components such as the entire reamer bridge and positioning pile trolley. The calculation results provide information for the optimization of the stress and fatigue of the detailed structure of these large components.
Other examples of detailed calculations include: the trunnion of the reamer bridge, the lying shaft and the locking pin, the hull, the double bottom, the positioning pile, the emergency backup positioning pile lifting system, the impact of the ship’s side, especially the barge when mooring, and many more.
The calculation of dynamic load is to understand the effect of vibration on the structure and limit the damage of fatigue. Based on these calculation results, various structures and their design details have been improved.
Leader Dredger also performed torsion calculations for each drive device on the ship. Not only did calculations for the various common systems such as the propulsion drive shaft and the reamer drive shaft, but also the impact of vibration on the entire structure were examined.
Other calculations include vibration calculations to reduce the vibration level of people and machines, and noise calculations to reduce the noise level in the cabin and the environmental noise level.
Leader Dredger also has dynamic simulation experiments, and the experimental data plays a vital role in dredger innovation.
For example, dynamic reaming operation simulation. The results of this simulation are used as input data for torsion, fatigue and stress calculations. The dynamic process of the positioning pile in the restricted free fall state is also simulated. This is a complicated system, that is, the positioning pile is suspended on its hoisting cable and falls. Through the hoisting wire rope, the brake on the hoisting winch can be used to control free fall. After the positioning pile hits the ground, a certain amount of slack will be formed in the steel cable, which needs to be retracted by the hydraulic cylinder of the wave compensator. A special multi-parameter simulation allows people to have an in-depth understanding of the dynamic process of positioning piles. The control system is improved based on the simulation results.
Integration Of Various Systems
Two principles have an important influence on the design of dredgers. They are all driven by diesel generator concepts and fully integrated with automation systems.
The concept of all driven by diesel generators is an important innovation for this type of dredger. Cutter suction dredger designed on this principle. A main diesel engine drives two generators to supply power to all electrical equipment, including cutter motors, mud pump motors, winch motors, hydraulic power packs and all other equipment. This has a huge impact on the design of the dredger. On the one hand, there is more freedom in the layout. On the other hand, the design must consider a large number of high-voltage cables, transformers and frequency converters. The motors used for the cutter drive and the underwater dredge pump are the same. Necessary considerations were made in the design to facilitate its replacement, thereby reducing downtime in the event of an accident.
All alarm systems are integrated into a control system. It is possible to monitor and control all subsystems through several workstations scattered throughout the ship.
The construction process is very elaborate. Where necessary, the welds are inspected by radiation. The structure of the hull, reamer bridge and positioning pile trolley has been carefully designed to limit vibration and stress concentration. In order to reduce stress concentration and avoid damage caused by fatigue load, especially in the structure of reamer bridge and positioning pile trolley:
- All edges are polished;
- All transition sections and structural changes are very smooth;
- All areas where the thickness of the steel plate changes are treated with bevel;
- The openings on the beams and bulkheads are made very round;
- Always install the support bracket;
- All welding is continuous, carefully processed and polished;
Positioning Pile, Steel Pile Trolley And Positioning Pile Lifting System
A lot of effort and innovation are required for the whole system consisting of positioning pile, positioning pile trolley and positioning pile lifting system. This is because of the ultra-conventional requirements of the system and the size and weight of the system. Therefore, every aspect needs to be reconsidered and tested. There are two positioning piles on the ship: the main positioning pile and the auxiliary positioning pile. The positioning pile is very heavy, and its weight and strength are at the optimal point. The side guide groove is made of very special steel, which can withstand the very large bending stress generated by the positioning pile. They also need to guide the hoisting cables and install hydraulic cylinders for emergency hoisting systems. Because the positioning piles rotate in the soil, they also need to lock the positioning piles from rotating relative to the dredger.
Special attention is paid to the manufacture and design of the positioning pile trolley. The special factors that need to be considered in the design are the characteristics of high strength, durability and wear resistance.
At first glance, the dredger looks very ordinary and very different. Because everything is proportional. However, hidden under the bright paint is a lot of effort and innovation of Leader Dredger. The net power, size and weight of the entire ship and many other components conceal many difficulties in design, manufacturing and operation.
Customized design and production of dredgers, Leader Dredger is professional